Risk factors for negative blood cultures in adult medical inpatients--a retrospective analysis.
BACKGROUND
The identification of clinical factors associated with negative blood cultures could help to avoid unnecessary blood cultures. C-reactive protein (CRP) is a well-established inflammation marker commonly used in the management of medical inpatients.


METHODS
We studied the association of clinical factors, CRP levels and changes of CRP documented prior to blood culture draws with the absence of bacteremia for hospitalized medical patients.


RESULTS
In the retrospective analysis of 710 blood cultures obtained from 310 medical inpatients of non-intensive-care wards during one year (admission blood cultures obtained in the emergency room were excluded), the following retrospectively available factors were the only independent predictors of blood cultures negative for obligate pathogens: a good clinical condition represented by the lowest of three general nursing categories (OR 4.2, 95% CI 1.8 - 9.5), a CRP rise > 50 mg/L documented before the blood culture draw (OR 2.0 95% CI 1.8-9.5) and any antibiotic treatment in the previous seven days (OR 2.0, 95% CI 1.1-3.5).


CONCLUSIONS
Including the general clinical condition, antibiotic pre-treatment and a substantial rise of CRP into the decision, whether or not to obtain blood cultures from medical inpatients with a suspected infection, could improve the diagnostic yield.
Ehrenstein
Boris P
BP
Dept. of Internal Medicine (I), University of Regensburg, Germany. boris.ehrenstein@klinik.uni-r.de
Ehrenstein
Vera
V
Henke
Christine
C
Linde
Hans-Jörg
HJ
Salzberger
Bernd
B
Schölmerich
Jürgen
J
Glück
Thomas
T
D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001424:Bacterial Infections / Q000175:diagnosis* / Q000188:drug therapy; D001431:Bacteriological Techniques; D015415:Biomarkers / Q000097:blood*; D001769:Blood / Q000382:microbiology*; D002097:C-Reactive Protein / Q000032:analysis*; D006801:Humans; D007297:Inpatients; D016015:Logistic Models; D012189:Retrospective Studies; D012307:Risk Factors
D000900:Anti-Bacterial Agents; D015415:Biomarkers; D002097:C-Reactive Protein